Technical Realisation of Digital TV Transmitter … ITU inter-regional seminar 1 Technical Realisation of Digital TV Transmitter Systems Friedrich Rottensteiner Rohde & Schwarz ITU

17TSP ITU inter-regional seminar

Technical Realisation of Digital TV Transmitter Systems

Friedrich Rottensteiner

Rohde & Schwarz

ITU inter-regional seminar


DVB-T Transmitter system

Technical Realisation of Digital TV Transmitter Systems

- MFN / SFN networks

- Transition from analog to digital

- state of the art transmitter family

- redundancy systems


MFN(multi frequency network)

SFN(single frequency network)

DVB-T transmitter systems

Network layout


SFN -network

Advantages of the SFN:

* Frequency efficiency- the DVB-T system use the SFN: one frequency for several programs

(current situation: each program has another frequency==> MFN: Multi Frequency Network)

- the SFN is with the factor of 3 better than the MFN's

* Power efficiency- lower transmitter power in the SFN is required because

- addition of all signal components from different transmitters and reflection at the receiving antenna

- with the lower transmitter output power: lower distortions in neighbor areas

- if gaps exists in the coverage (deep valley, tunnels, etc.): these gaps can be filled


SFN-network

Disadvantages of the SFN:

* the TS is equal at all transmitter sites (no local program can be introduced)

* a transmitter which violates the SFN rules is a jammer in the coverage

* synchronization (time, frequency, information) is necessary

* network monitoring is necessary to control the SFN features


DVB-T transmitter chain SFN

MPEG-2remultiplexer

SFNadapter

MPEG-2TS

TXNetworkadapter

DistributionNetwork

RXNetworkadapter

RXNetworkadapter

GPS*

10 MHz 1 pps

DVB-Tmodulator

SYNCsystem

GPS*

10 MHz 1 pps

DVB-Tmodulator

SYNCsystem

GPS*

10 MHz 1 pps

* Could be any common available frequency reference

MPEG-2TS

MPEG-2TS


DVB-T transmission network (via Satellite)

Transmitter n

Private NNI

Transmitter 1

Private NNI

TV digitalMPEG 2 + DVB-S


DVB-T transmission network (via Radio Link/dark fiber)


DVB-T transmission network (via ATM/SDH)

Private UNI

Private UNI

Private NNI

Public UNI

Public UNI

Public NNI

Public NNI

Public NNI

B ISDN

NET 1

NET 2

digital Studio 1

MPEG 2

digital Studio 2

MPEG 2

digital Studio n

MPEG 2

Transmitter n

Private NNI

Transmitter 1

Private NNI

MUX MIPinserter

NetworkAdapter

GPS1 pps

GPS1 pps

GPS1 pps


DVB-T network monitoring


DVB-T networks monitoring

program sourceprogram - TS

data rate entire TSsingle programselementary streams

protocol-parameter

parameters of1. priority2. priority3. priority

tables presencerepetition rate

picture quality DVQL - WDVQL - UTASA

event protocol all unusual events summedup in REPORT

program sourcemeasurement-TS

repeatable measurementsequences for comparablemeasurements

MIP insertion monitoring ofPID, synchronisation info,GPS 1pps

modulation links modes radio link (HDB3, QPSK)satellite (QPSK)dark fibreATM over SDH/PDH


DVB-T transmitter monitoring

transmitteroutput

RF parameters accuracy of frequencyphase noise of LOaverage level and max. peaklevel in RF and IFamplitude vs frequencyphase vs frequencyC/N and intermodulationshoulder distancepower efficiency

parameters afterdemodulation

QPSK/QAM parameters in2k/8k modeconstellation diagramBER, MER, ENDTPSsignal delay from TS @transmitter input to antenna


DVB-T Transmitter

TS transfare viaradio linksatellitefiber ......

DVB-T transmitter RF output

1

2

switch possition:position 1 exciteroutput BER 2*10-4 nach Viterbi @ Noise 1

position 2 DVB-T transmitteroutput BER 2*10-4 nach Viterbi @ Noise 2

END = Noise 2 - Noise 1

DVB-T demodulator BER measurment

exciter RF output


DVB-T realisation of digital transmitter stations

Transition fromanalog to digital


Requirements for the engineering work

Definition of the intended coverage area in relation to the existing analog TV Service(area , population, channel, power).

Investigation of possible limitation by interference of other services in this area

Result: Selection of "free channels" to choose for licensing in terms of frequency and radiated power.



Technical planning of the station

- Investigation of the existing antenna

Result: dependent on the desired coverage area (omnidirectional, sectional, beam) and mechanical (static) situation define modification and antenna gain.

- Calculate necessary transmitter power

- Space requirement for transmitters



Alternativ: transition of the excisting analog transmitter into digital service

- Change of encoder module in exciter

- bypassing of the sound part (amplifier and v/s diplexer)

- introducing of DVB-T band - filter

- new equalizing of transmitter



Transmitter DVB-T /Analog(combined)

Block Diagram NH/NV7000


Transmitter analog(split)

10 kW

RF

harmonic-filter lightning

protection

6 x VH602

amplifier VH602

dB

integrated power supply

exciter A

ATVencoder

inputs

AF1 AF2

digitalprecorrector

I / Qmodulator

I

Q

I

Q

exciter Binputs

AF1 AF2

I

Q

I

Q

optional

vision

sound

vision/sound diplexer

-4,43-notch filterr

synthesizer

VF1VF2

VF1VF2

ATVencoder

digitalprecorrector

I / Qmodulator

synthesizer


Block Diagram 1,3 kW DVB-T Transmitter

DVB-T transmitter NV7000

1,3 kW rms

DVB-T TransmitterNV7130 1,3kWrms

RF

harmonics-filter lightning-

protectionchannel-

filter

optional

amplifier VH602

dB

built-in power supply

exciter A

EncoderDVB-T

input ASI HP1 HP2

LP1 LP2

digitalprecorrector

I / QModulator

I

Q

I

Q

exciter B

EncoderDVB-T

input ASI HP1 HP2

LP1 LP2

digitalprecorector

I / QModulator

I

Q

I

Q

optional

RF


PAL-nonlinearity

Black picture Black picture

Frequency response in channel

bl/wi-amplification


DVB- Transmitter nonlinearity

frequencyresponse Constellation Diagramm 64QAM


DVB-T Crest Faktor

Uss / 2 = Us = 6 (ca.) normalised to U rms

Urms= 1

U clipin Transmitter

analog digital


Example of a radiated signal from a TV station

Interference from analog to digital service

Interference from digital to analog service

2MHz/DIV

10dB/DIV

DVB-T DVB-T

Mixed Operation Analog / Digital

in adjacent channelsP A L



+0,5

0

-1,0

-20

-30

-40

-50

-60

-12 -10 -8 -6 -4 -2 F centre 2 4 6 8 10 12

UHF Channel N-1 UHF Channel N UHF Channel N+1

-4MHz/0,5dB 4MHz/0,5dB

-3,805MHz/-1,0dB 3,805MHz/-1,0dB

-4,3MHz/-36dB 4,3MHz/-36dB

Relative Spectral Density (dB)

Frequency relative to Multiplex Centre (MHz)

Transmitter Output Spectral Mask after the Bandpass Filter

-10,25..-6MHz/-45dB 6...10,25MHz/-45dB

Tg=-250ns

Tg=250ns

Ref.

(Frequency Response)

Groupdelay



8 cavity filters

3dB couplers

narrow band input

broadbandinput

output

insertion loss / dB

frequency / MHz

f-center2 4 6 8 10 MHz-10 -8 -6 -4 -2



0

10

20

30

40

50

60

70

80

90

100

Bitrate [Mbit/s] Tg/Tu = 1/4

Min

imu

m m

edia

n f

ield

str

eng

th [

dB

uV

/m]

FX QPSK FX 16 QAM FX 64 QAM

Port A QPSK Port A 16 QAM Port A 64 QAMPort B QPSK Port B 16 QAM Port B 64 QAM






Modulation Code Rate

Nutzträger 6048Takt [MHz] 9 1/7 9 1/7 9 1/7 9 1/7Guard interv. 1/4 1/8 1/16 1/32n*T 8192 8192 8192 8192Tu [us] 896 896 896 896n*T 2048 1024 512 256d [us] 224 112 56 28n*T 10240 9216 8704 8448Tu+d [us] 1120 1008 952 924

Modulation 64 QAM Bit/Träger 6Code Rate

Guard interv. 1/4 1/8 1/16 1/32max. Rate [Mbit/s] 2 1/2 4,98 5,53 5,85 6,03

2 2/3 6,64 7,37 7,81 8,04 2 3/4 7,46 8,29 8,78 9,05 2 5/6 8,29 9,22 9,76 10,05 2 7/8 8,71 9,68 10,25 10,56

max. Rate [Mbit/s] 4 1/2 9,95 11,06 11,71 12,06

1/2

2 2 /3

2 3 /4

2 5 /6

2 7 /8

2 1/2

4 2 /3

4 3 /4

4 5 /6

4 7 /8

4 1/2

6 2 /3

6 3 /4

6 5 /6

6 7 /8

6

1/4

1/8

1/16

1/320

5

10

15

20

25

30

35

ne t data rates

[Mbps]

code rate of inner error protection /bits per sub-carrier

guard interval

DVB-T net data rates


DVB-T transmitter system

The new UHF transmitter family NH/NV7000

for analog and digital TV transmitters

- High Power -

Innovation and experience

for the benefit of the broadcaster



Power Supply

Air Cooling System

Modulator / ExciterSH700 ATV Splitt Ampl. / SC700 ATV Combined Ampl. / SV700 DVB-T

VH6022kW/400W

Control and Monitoring

LDMOS Amplifier Modules 470 - 860 MHz

Power Supply integrated in VH602

Liquid Cooling System

High Power TxATV: 3,5kW ... 40kW

DVB-T: 800W ... 10kW

NH/NV7000 Component Structure and System Family

Medium Power TxATV: 250W ... 2kW

DVB-T: 100W ... 800W

VH650 500W/200W


l Economical

l Compact

l State of the art

l Modular design

l Expandable

l Easy to handle


TARGETS for NH/NV7000

Transmitter: Medium Power air cooled

Transmitter: High Power liquid cooled


Liquid Cooled Transmitter / Amplifier


10kW ATV / 2,5 kW DVB-T transmitter into one rack

VH602 LDMOS amplifier


DVB-T transmitter system Overview NV/NH7000

System configuration for liquid cooling

AnalogModulator

DVB-TModulator

Exciter

Combin

er

DVB-T Filter

Harmonics and

Trap FilterAmplifier incl. PS

Pump System Heat Exchanger

Controlling and

Monitoring

VH602


NH/NV Power Classes

Number ofAmplifier Module

(+ Sound Amp. Modulefor ATV)

ATVPsync

DVB-TPeff (36dB shoulder)

2 (+1*) 3,5 kW 800 W

3 (+1*) 5 kW 1,3 kW

4 (+2) 7 kW 1,7 kW

6 (+2) 10 kW 2,5 kW

8 (+2) 13 kW 3,4 kW

12 (+2) 20 kW 5 kW

* optional 2

NH/NV7000 High Power

Further combination: 2*13kW and 2*20kW in active reserve3*10kW


Redundancy in power

Output Power with Breakdown of Amplifiers:2

−∗=m

nmratedPoutP

Pout = real output powerPrated = nominal output powerm = number of amplifiersn = number of defect amplifiersfor example: m=8, n=1 ⇒ Pout = 0.766 x Prated


Cooling Concept Amplifier

l Closed loop of liquid through onepipe with continuous identical diameter into the amplifier heat sink(corrosion-less material in stainlesssteel and aluminium)

l Internal blower for transfer of remainder heat to watercooler, thus preventing any hot spot

l Transistors mounted directly on top of cooling pipe

l DT input / output amplifier < 3°C

l Junction temperature < 120°Cat 24°C ambient temperature

VH602 Amplifier and Power Supply


VH602 Block Diagram

0,4mW

65W

15W

2mW

65W

15W

2kW

PSYNC

PDVB

0,4mW

65W

15W

2mW

65W

15W

2kW

PSYNC

PDVB

0,4mW

65W

15W

2mW

65W

15W

2kW

PSYNC

PDVB

0,4mW

65W

15W

2mW 10W

2W

60W

270W65W

15W

440W

2kW

PSYNC

PDVB

270W

60W

digital

analog

VH602 Amplifier and Power Supply


M

T1 P1 P1

Ball valve

M

Flexi tubing

Safety valve

Flow control monitor

Check valve

3-way mixer

Drain valve

Expansion vessel

Heatexchanger

Pump

air-vent valve

Water Cooling System for the transmitter NV6000

Liquid Cooling System


Multistandard Exciter SX700

CCU

Synthesizer

Modulator

ATV/DVB Encoder

Digital Pre-Corrector

Power supply


Block Diagram

TS LP A /VIDEO_MON

TS HP A /VIDEO 1TS HP B /VIDEO 2

1PPS INT

RS232

RS232_FLASH

1PPS_EXT

TS LP B

I_VIDEO

Q_VIDEO

I_AUDIO

Q_AUDIO

DigitalInterface(14 Bit)

I_VIDEO

Q_VIDEO

I_AUDIO

Q_AUDIO

AnalogueInterface

RF_VIDEO

RF_AUDIO

LOCAL

REF_EXT

GPS_ANT

CONTROL

INT_REF (120MHZ)

DVB-Encoder:- MIP-Decoder- SFN Function- Channel Coding and Modulation

or

ATV-Encoder:- digital Video- and Audio processing- multi Standard- optional NICAM or Std M module

ATV/DVB-Precorrector:- Groupdelay Corrector- Linear Precorrector for DVB and ATV split and combined- D/A-Conversion

ATV/DVB-Synthesizer:- 10 MHz local Ref-PLL- Band III, IV and V- optional internal GPS- module

RF_CHECK

ATV/DVB-Modulator:- analogue I/Q-Modulation into RF for Video and Audio Band III, IV and V- Output Filter for Video and Audio- Output Amplifier- RF Checker

RS485

RS485 RS232

RS232

Dis

pla

yun

it

Central Control Unit

TTL-Bustopar. Interface

Control Bus toAmplifiers, Switches,Blowers, ...

Exciter SH/SC/SV700


NetLink

Remote interface


Monitoring and Controlling System

l User-friendly monitoring software on one large display

l Additional PC software (GUI) with very comfortable graphical presentation and high level of information

l One interface for the all parameters ofthe exciter (incl. encoder and GPS-receiver in case of DVB-T)

l Multiple possibilities of remote control- Bitbus (RS485)- RS232 with TNPP protocol

-> modem option- NetLink for SNMP interface or

WEB-based supervision system- Parallel interface

Remote interface

BITBUS-Gateway

(Option)

Modem(Option)

CCU : Central Control UnitSV700 : Exciter DVB-TSH700 : Exciter Analog-TV (Split)SC700 : Exciter Analog-TV (Combined)RC : Rack Control

B

Amplifier

GS

Amplifier

A

RC

GUI

(Graphical UserInterface)

com

1

BSV700

SV700

(SH700)

A

com

1

com

2

Encoder

RS 232(TNPP) RS 232

(TNPP)

RS 232

RS 485

(BITBUS acc. to IEC 864-2)

PSTN(TNPP)

F1 F2 F3 F4 F5

+ + +

+

+++com 1

com 1 com 4 I / O

com

3co

m 2

RESETRS 232

ESCAPE TAB

- +

RS 485

RS 485

ENTER

I/O

ParallelInterface

Signals

Commands

RC

Web-Server/SNMP-Agent

(Option)

Ethernet

(TCP/IP or SNMP)

REMOTE CONTROL

TRANSMITTER CONTROL UNITROHDE&SCHWARZ

(Option)

Equal. Synth. IQ-Mod.

(SC700)


Overview on Protocol Types and Layers

Web-Browser HP Openview

TCP(Transport Control Protocol)

Transport(Layer 4)

UDP(User Datagram Protocol)

HTTP(Hyper Text Transfer Protocol)

SNMP(Simple Network Management Protocol)

Application(Layer 7)

IP(Internet Protocol)

Network(Layer 3)

3. NetLink Unit for Remote Control


WEB-Server Application (Supervision System over TCP/IP)Transmitter Station Network Control Centre / Mobile Staff

Server Client

Laptop with standard WEB-browser

Management system (Windows, Unix, Linux, Mac) with standard Web-browser

Firewall

Internet / Intranet(TCP/IP)

• Ethernet (LAN/WAN)

NetLink

IntegratedWEB-serverfrom R&S

4. NetLink WEB-Server


SNMP ApplicationTransmitter Stations Network Control centres

Management platform(e.g. HP openview)

and SNMP network manager(software)

SNMP Network

• Ethernet (LAN/WAN)

ServerNMS

SNMP Traps (Alarms)

R&S delivery part

NetLinkIntegrated

SNMP agentfrom R&S

5. NetLink SNMP-Agent

SNMP agentTx from

Supplier X


TransmitterRedundency Systems


Dual drive, single PA stage

OFDMMod.A Exciter A

OFDMMod.B Exciter B

TS

TS

PAband pass

filter

TVSS

RF out

D.L.

3 port U-linkpanel

antenna


Dual drive, double PA stage, U-link patching

OFDMMod.A Exciter A

OFDMMod.B Exciter B

TS

TS

PA A

PA B

3 dB coupler

D.L.

absorber

band passfilter

TVSS

RF out antenna

RF U-link patch panel


Dual drive, double PA stage, RF relay switch

OFDMMod.A Exciter A

OFDMMod.B Exciter B

TS

TS

PA A

PA B

3 dB coupler

D.L.

absorber

band passfilter

TVSS

RF out antenna

RF relaysautomaticswitching


Passive stand-by

OFDMMod.A Exciter A

TSPA A

band passfilter

TVSS

RF out

D.L.

OFDMMod.B Exciter B

TSPA B

antennaRF relay


Passive stand-by with dual drive

OFDMMod.A Exciter A

TSPA

band passfilter

TVSS

RF out

D.L.

OFDMMod.B Exciter B

TSPA

antenna


Passive-/active stand-by for half antenna

OFDMMod.A Exciter A

OFDMMod.B Exciter B

TS

TS

PA A

PA B

3 dB coupler

D.L.

absorber

band passfilter

TVSS

RF out

TVSS

RF out

UA

LA


N+1 Reserve System

Programm 1

DVB-T transmitter n+1

1 2 n R

CCU

Programm 2 Programm n

ASI crossbar switch

Reserve concepts


Conclusion

Benefits for the broadcaster

þ Extremely compact design

þ Improved technology for exciter, amplifier andcooling system

þ Low operational cost

þ More flexibility for installation

þ More flexibility for remote control

þ High commonality of sub-modules for reduced spares inventories

þ Easy transition from analogue to digital secures investment


References:

ETS 300 744 Digital Video Broadcasting (DVB); Framing structure, channel coding and

modulation for digital Terrestrial television (DVB-T).

ETR 290 Digital Video Broadcasting (DVB); Measurement guidelines for DVB systems.

TR 101 190 Digital Video Broadcasting (DVB); Implementation guidelines for DVB

terrestrial services; Transmission aspects. (TR 101 190).

TM 1925 Digital TV Transmitter Performance Specification.

(AC106 VALIDATE Del.14)

Documents

Technical Realisation of Digital TV Transmitter … ITU inter-regional seminar 1 Technical Realisation of Digital TV Transmitter Systems Friedrich Rottensteiner Rohde & Schwarz ITU